The present invention relates to a long-range optical device having at least one tube, in which an optical system is positioned, having at least one image stabilization unit, which is designed for the purpose of moving at least one optical assembly of the optical system relative to the at least one tube, having at least one signal processing unit, which is designed such that it actuates or controls at least one image stabilization unit in one mode of a plurality of modes, wherein a respective movement situation of the long-range optical device is assigned to each mode, and having a mode detection unit, which is designed such that it determines the mode from the plurality of modes.
Furthermore, the present invention relates to a method for determining a mode for an actuation of an image stabilization unit in a long-range optical device, wherein the image stabilization unit is actuated in one mode of a plurality of modes, wherein a respective movement situation of the long-range optical device is assigned to each mode.
The long-range optical devices in the scope of the present invention can be in particular monocular or binocular telescopes. Therefore, when reference is made hereafter to a monocular or binocular telescope, however, this is not to be understood as restrictive in any way with respect to the type of the long-range optical device. Fundamentally, these can also be long-range optical devices other than modular or binocular telescopes, for example a camera.
Long-range optical devices frequently have image stabilization, to compensate for shaky rotational movements of the long-range optical device. The shaky movements can originate from a user of the long-range optical device, who holds the long-range optical device in front of his eyes, but can also be caused by a specific supporting surface, for example if the user is located on a ship. The shaky movements typically occur primarily around a vertical axis and a transverse axis of the long-range optical device. Under these shaky rotational movements, a visible image resolution suffers and small image details are made non-recognizable. In addition, the blurred image is frequently perceived to be annoying by a user.
Therefore, various proposals for types of the image stabilization have been made in the prior art. For example, solely mechanical image stabilizations are known. These can act solely passively, for example like an eddy current brake. However, active systems are also known, which act on an image stabilization unit by means of actuators.
In particular, the actuators of an active mechanical image stabilization system can be embedded in a control loop, wherein the actuators are actuated or controlled by a central signal processing unit of the long-range optical device. The type of the optical elements which are acted upon by means of the image stabilization unit in order to cause the image stabilization can also differ. Various possible solutions for this purpose were proposed in the prior art, for example the reversal system, which can be a lens reversal system or a prism reversal system, for rotation relative to a tube or housing element of the long-range optical device around one or more axes or moving the objective or a part of the objective perpendicularly to an optical axis of the long-range optical device. Solely software-based implementations of image stabilization are also possible, in particular in cooperation with digital image recording. Except in solely passively operating mechanical systems, a use of the present invention is fundamentally conceivable with all other types of image stabilization.
In the case of image stabilization, it is desirable for a compensation of the movements of the long-range optical device because of external influences to only be performed when the movements are unintentional. These unintentional movements are designated in the scope of this application as shaky movements or shaky rotational movements. However, intentional movements are to be differentiated therefrom, for example when a user pivots the long-range optical device to observe a different object, or when the user follows a moving object during an observation. Of course, no compensation of the movement is to occur during these intentional movements. Otherwise, behaviour of the long-range optical device which is irritating for the user would initially occur, because the image would remain stationary although he pivots the long-range optical device. Furthermore, an image stabilization unit would reach a maximum possible compensation or deflection from a certain movement extent and stop there.
Therefore, a unit which is referred to as a mode detection unit hereafter is typically provided in the long-range optical devices, which can be implemented as hardware and also as software. The mode detection unit can be provided separately, but also as part of the central signal processing unit, for example, and is used for the purpose of differentiating between undesired shaky rotational movements and intentional pivot or tilt movements. Therefore, it differentiates between various movement situations, to each of which a corresponding mode of the image stabilization is assigned, and which takes into consideration the character of the movement situation, i.e. whether it is unintentional or intentional. Various proposals have already been made for the differentiation between various movement situations or the accompanying establishment of a mode of the image stabilization, respectively.
Thus, for example, the publication DE 199 37 775 A1, shows a level detector, which detects a current angular velocity signal and on the basis of a threshold value comparison assumes an influence on the type of the actuation of an image stabilization unit, for example in that a high-pass filter and an integrator unit of the angular velocity signal are bypassed.
The publication U.S. Pat. No. 6,384,976 B1 also shows the determination of the mode of the image stabilization on the basis of a comparison of an angular velocity signal to a fixed threshold value. If a threshold value is exceeded, a changeover into another mode occurs. If the value falls below the same threshold value or another threshold value again, it switches back into the original mode.
The publication EP 1 980 904 A2 also shows a differentiation between various modes of image stabilization on the basis of a comparison to a specific threshold value.
The publication EP 1 708 019 A1 proposes carrying out a comparison to a fixed threshold value, in this case on the basis of a correction value which is calculated by a central data processing unit for the actuation of the image stabilization unit.
The publication EP 0 587 432 B1 proposes detecting a pivot of the long-range optical device both from the curve of an angular velocity and also from the curve of an angle resulting therefrom. A pivot always exists if a constant angular velocity and a monotonously increasing angle are provided. If a pivot exists, the limiting frequency of a high-pass filter is increased, so that a low-frequency pivot movement is filtered.
Finally, another isolated proposal in the publication U.S. Pat. No. 5,444,509 A is concerned with using a measured angular velocity and its first derivative and its second derivative to actuate an image stabilization unit.
To differentiate between a plurality of modes or to determine a specific mode for the image stabilization, respectively, the prior art thus proposes performing a decision about the existence of a specific image stabilization mode or a pivot procedure for each coordinate direction separately from a comparison of a corresponding angular velocity to a fixed threshold value or from an observation of a curve or profile of the angular velocity. However, a comparison solely of an angular velocity to a fixed value unchangeably influences the behaviour of the long-range optical device. If such a threshold value is configured excessively low or excessively high, for example an intentional movement of the long-range optical device is recognized, although the movement is actually not intentional. Furthermore, it can occur that a very slow intentional pivot or tilt movement is not recognized as an intentional movement and is therefore compensated for by the image stabilization. This is true in particular in the event of a separate observation of the various movement directions. A pivot detection on the basis of an observation of the curve of angular velocity and corresponding angle typically has the result that a beginning of a pivot procedure or an intentional movement is detected excessively late and an end of the pivot procedure or the intentional movement is detected excessively early, so that sometimes an incorrect image stabilization mode is applied.